Communication systems and secure communications in such systems are known. Typically security is provided using some form of crypto key to encrypt information that is sent from the originator or sending party or unit. The target or receiving party or unit then decrypts this information using the same or a corresponding crypto key to yield the information in its original form. To enhance security the crypto key may change from time to time, for example with every frame. Typically this change is a deterministic change that depends on the state of the encryption or decryption processes. The originating unit and target unit have to make sure their crypto keys are synchronized or else the target unit will not be able to successfully decrypt the information. Given the deterministic nature for the change this is straight forward, except, for example, when a frame or packet is added, such as for example an overhead packet added by the system, in which case crypto synchronization may be lost. Known approaches sometimes devote entire frames or packets or other overhead means just to synchronization information, but this tends to waste channel capacity or result in long delays to re-establish synchronization and thus poor audio quality.